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  <title>Defines a set of constants for retrieval and mass-definition</title>
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  <div id="layout-content"><div id="function.apc-define-constants" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">apc_define_constants</h1>
  <p class="verinfo">(PECL apc &gt;= 3.0.0)</p><p class="refpurpose"><span class="refname">apc_define_constants</span> &mdash; <span class="dc-title">
   Defines a set of constants for retrieval and mass-definition 
  </span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.apc-define-constants-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>apc_define_constants</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$key</code></span>
   , <span class="methodparam"><span class="type">array</span> <code class="parameter">$constants</code></span>
   [, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$case_sensitive</code><span class="initializer"> = <strong><code>TRUE</code></strong></span></span>
  ] ) : <span class="type">bool</span></div>


  <p class="para rdfs-comment">
   <span class="function"><a href="define.html" class="function">define()</a></span> is notoriously slow. Since the main benefit of
   APC is to increase the performance of scripts/applications, this mechanism
   is provided to streamline the process of mass constant definition. However,
   this function does not perform as well as anticipated.
  </p>

  <p class="para">
   For a better-performing solution, try the
   <a href="http://pecl.php.net/package/hidef" class="link external">&raquo;&nbsp;hidef</a> extension from PECL.
  </p>

  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <span class="simpara">
    To remove a set of stored constants (without clearing the entire cache), an
    empty array may be passed as the <code class="parameter">constants</code>
    parameter, effectively clearing the stored value(s).
   </span>
  </p></blockquote>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.apc-define-constants-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">key</code></dt>

     <dd>

      <p class="para">
       The <code class="parameter">key</code> serves as the name of the constant set
       being stored. This <code class="parameter">key</code> is used to retrieve the
       stored constants in <span class="function"><a href="apc_load_constants.html" class="function">apc_load_constants()</a></span>.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">constants</code></dt>

     <dd>

      <p class="para">
       An associative array of <em>constant_name =&gt; value</em>
       pairs. The <em>constant_name</em> must follow the normal
       <a href="language.constants.html" class="link">constant</a> naming rules.
       <em>value</em> must evaluate to a scalar value.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">case_sensitive</code></dt>

     <dd>

      <p class="para">
       The default behaviour for constants is to be declared case-sensitive;
       i.e. <em>CONSTANT</em> and <em>Constant</em>
       represent different values. If this parameter evaluates to <strong><code>FALSE</code></strong> the
       constants will be declared as case-insensitive symbols.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.apc-define-constants-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
  </p>
 </div>



 <div class="refsect1 examples" id="refsect1-function.apc-define-constants-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-403">
    <p><strong>Example #1 <span class="function"><strong>apc_define_constants()</strong></span> example</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$constants&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'ONE'&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'TWO'&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'THREE'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">3</span><span style="color: #007700">,<br />);<br /></span><span style="color: #0000BB">apc_define_constants</span><span style="color: #007700">(</span><span style="color: #DD0000">'numbers'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$constants</span><span style="color: #007700">);<br />echo&nbsp;</span><span style="color: #0000BB">ONE</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">TWO</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">THREE</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
123
</pre></div>
    </div>
   </div>
  </p>
 </div>



 <div class="refsect1 seealso" id="refsect1-function.apc-define-constants-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="apc_load_constants.html" class="function" rel="rdfs-seeAlso">apc_load_constants()</a> - Loads a set of constants from the cache</span></li>
    <li class="member"><span class="function"><a href="define.html" class="function" rel="rdfs-seeAlso">define()</a> - 定义一个常量</span></li>
    <li class="member"><span class="function"><a href="constant.html" class="function" rel="rdfs-seeAlso">constant()</a> - 返回一个常量的值</span></li>
    <li class="member">
     Or <a href="language.constants.html" class="link">the PHP constants reference</a>
    </li>
   </ul>
  </p>
 </div>


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